Lennox Pulse Furnace Repair Manual

The Lennox Pulse Furnace is a high-efficiency gas furnace featuring pulse combustion technology, electronic ignition, and advanced heat exchanger design. This manual covers safety procedures, troubleshooting, component identification, maintenance schedules, and repair instructions for models G14, GSR14, and similar Pulse series units. Below are key sections for safety warnings, technical specifications, diagnostic procedures, and repair guidelines.

1. Safety Precautions 2. Model Identification 3. Technical Specifications 4. Component Overview 5. Diagnostic Procedures 6. Common Repairs 7. Maintenance Schedule 8. Error Code Troubleshooting 9. Parts Replacement 10. Wiring Diagrams 11. Technical Support

Safety Precautions

Critical safety information for working with Lennox Pulse furnaces.

Hazard	Precaution
Gas leaks	Shut off gas supply immediately; ventilate area
Electrical shock	Disconnect power at breaker before servicing
Carbon monoxide	Install CO detectors; ensure proper venting
Hot surfaces	Allow furnace to cool before servicing
Combustion gases	Wear appropriate respiratory protection

WARNING! Always verify gas valve is closed and power is disconnected before beginning repairs.

Model Identification

Locate model and serial numbers on furnace rating plate.

Model number: Typically begins with G14, GSR14, or similar
Serial number: Used for parts identification and age determination
Rating plate location: Inside burner compartment door
Manufacturing date: Encoded in serial number (first four digits)

Note: Always verify correct model before ordering replacement parts.

Technical Specifications

Input Capacity: 40,000-140,000 BTU/hr depending on model
AFUE Rating: Up to 96.7% efficiency
Gas Type: Natural gas or LP/propane (conversion kit required)
Electrical: 120V AC, 60Hz, 3-8 amps
Venting: PVC plastic pipe required
Combustion Technology: Pulse combustion with spark ignition
Heat Exchanger: Stainless steel pulse combustion chamber
Dimensions: Varies by model (typically 21"W x 26"D x 40"H)

Component Overview

Key components of Lennox Pulse furnace system.

Main Components: Pulse combustion chamber, gas valve, igniter, pressure switch, flame sensor, blower motor, control board, heat exchanger, vent system.

Gas Valve: Regulates gas flow to combustion chamber. Pressure Switch: Verifies proper venting operation. Igniter: Provides spark for combustion. Flame Sensor: Detects presence of flame. Control Board: Manages furnace operation and diagnostics. Blower Motor: Circulates air through heat exchanger.

Diagnostic Procedures

Systematic troubleshooting approach for common issues.

Verify power and gas supply
Check thermostat settings and wiring
Inspect pressure switch operation
Test igniter and flame sensor
Examine control board LED status
Measure gas pressure at valve
Check vent system for obstructions

Tip: Always start with simplest solutions before proceeding to complex diagnostics.

Common Repairs

Frequently required repairs for Lennox Pulse furnaces.

Igniter replacement: Remove old igniter, install new unit
Flame sensor cleaning: Remove and clean with emery cloth
Pressure switch replacement: Test with manometer first
Gas valve service: Check for proper voltage and pressure
Blower motor maintenance: Clean and lubricate as needed
Heat exchanger inspection: Check for cracks or corrosion
Control board repair/replacement: Diagnose with multimeter

WARNING! Gas valve repairs should only be performed by qualified technicians.

Maintenance Schedule

Recommended maintenance intervals for optimal performance.

Interval	Maintenance Task
Monthly	Check air filter; replace if dirty
Annually	Professional inspection and cleaning
Every 2 years	Heat exchanger inspection
Every 5 years	Complete system overhaul

CAUTION! Neglecting maintenance can void warranty and create safety hazards.

Error Code Troubleshooting

Diagnostic codes and recommended actions.

Code	Description	Solution
1 Flash	Pressure switch stuck open	Check venting, replace pressure switch
2 Flashes	Pressure switch stuck closed	Replace pressure switch
3 Flashes	Ignition failure	Check gas supply, igniter, flame sensor
4 Flashes	Limit circuit fault	Check airflow, filters, blower operation
5 Flashes	Flame sensed with gas off	Replace gas valve or control board

Parts Replacement

Common replacement parts and procedures.

Igniter: Part #10W22; requires disconnecting wires and mounting screws
Flame Sensor: Part #20C56; clean or replace as needed
Pressure Switch: Part #27H56; test with manometer before replacement
Gas Valve: Part #47H56; requires gas line disconnection
Control Board: Part #51M38; note wiring configuration before replacement
Blower Motor: Part #46H56; check capacitor when replacing

Wiring Diagrams

Reference wiring schematics for electrical troubleshooting.

Control board connections: 24VAC thermostat circuit, 120VAC power input, gas valve wiring, pressure switch circuit, igniter connections, blower motor control.

Note: Always disconnect power before testing electrical components. Use multimeter to verify voltages and continuity.

Technical Support

Contact information and additional resources.

Lennox Customer Support: 1-800-9-LENNOX (1-800-953-6669). Website: www.lennox.com. Technical Documentation: Available through Lennox dealer portal. Parts Ordering: Contact authorized Lennox dealers.

Service Note: Many Pulse furnace repairs require specialized training and tools. Consider professional service for complex issues.